Klinefelter syndrome is highly underdiagnosed and diagnosis is often delayed. With the introduction of non‐invasive prenatal screening, the diagnostic pattern will require an updated description of the clinical and biochemical presentation of infants with Klinefelter syndrome. In the first months of life, the hypothalamic–pituitary–gonadal (HPG)‐axis is transiently activated in healthy males during the so‐called minipuberty. This period represents a “window of opportunity” for evaluation of the HPG‐axis before puberty and without stimulation tests. Infants with Klinefelter syndrome present with a hormonal surge during the minipuberty. However, only a limited number of studies exist, and the results are contradictory. Further studies are needed to clarify whether infants with Klinefelter syndrome present with impaired testosterone production during the minipuberty. The aim of this review is to describe the clinical and biochemical characteristics of the neonate and infant with Klinefelter syndrome with special focus on the minipuberty and to update the clinical recommendations for Klinefelter syndrome during infancy.

中文翻译：

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Klinefelter综合征的青春期：现状和未来方向。

Klinefelter综合征的诊断严重不足，诊断通常会延迟。随着非侵入性产前筛查的引入，诊断模式将需要更新描述克氏综合征婴儿的临床和生化表现。在生命的最初几个月中，健康男性的下丘脑-垂体-性腺（HPG）轴在所谓的青春期短暂激活。这个时期代表了青春期之前没有进行刺激测试的HPG轴评估的“机会之窗”。Klinefelter综合征的婴儿在青春期出现激素激增。然而，仅存在有限的研究，并且结果是矛盾的。需要进行进一步的研究来阐明患有克氏综合征的婴儿在小青春期是否存在睾丸激素产生受损的情况。这篇综述的目的是描述克氏综合征的新生儿和婴儿的临床和生化特征，特别关注小青春期，并更新婴儿期克氏综合征的临床建议。